Mac Pro review

Apple lays the PowerPC architecture to rest with the introduction of the new …

PCI Express and other goodies

Similar to its predecessor, the Mac Pro offers three additional PCI Express expansion slots. What's particularly nice is that slot 1 is double-wide, meaning that you can drop in a monster video card without it blocking another open slot.

At top are the four PCIe slots. The RAM risers are below

The slots themselves are fed from both the north- and southbridges, using a set of muxes to determine what slots are fed and from which chip. Ultimately, they all end up back at the northbridge.

By default, the Mac Pro is configured with slot 1 set at 16 lanes (x16), slot 2 at x1, and slots 3 and 4 at x4. The AirPort Express slot mentioned above uses a single lane. If you don't like that set-up, you can switch from x16, x1, x4, x4 to one of the following configurations:

x8, x8, x1, x8

x8, x8, x4, x4

x16, x1, x1, x8

The last one would appear to the best if you're adding another video card. I've got an ATI Radeon X1900XT on order, which I'll drop to slot 1 while moving the NVIDIA GeForce 7300GT over to slot 4. Unfortunately, the lack of ability to have two 16-lane slots going at the same time rules out x16 Crossfire and SLI configurations. This is a limitation of the Intel 5000X chipset, which can only support 28 total PCI Express lanes. Assuming Crossfire or SLI video cards become available for the Mac Pro, there is no reason why it wouldn't be able to handle an x8 Crossfire or SLI configuration.

CPUs and heatsink

As we come to the bottom of the case, we find the fan (maybe a bit bigger than that of the G5 tower) located directly under the first hard drive bay. Directly under the AirPort/Bluetooth area is where our trusty Xeon 5150s live. Mac reseller PowerMax Computers took the first Mac Pro they received apart and graciously allowed us to use these pictures.

The heatsinks inside and outside of the case

As you can see, the heat sinks are very large. Way down at the bottom of all that cooling goodness are the Xeons themselves.

You gotta have fans

It's obvious that the switch to the Xeon 5100 series eliminated most of the cooling headaches Apple had with the PowerPC 970 processors. To refresh your memory, check out the liquid cooling and heatsink contraption from the Dual 2.5GHz Power Macintosh G5.

Remember these?

That appears to be the most significant factor in the redesign of the interior space. Less space needed for cooling very hot processors means more space for useful things like hard drives and DVD burners.

RAM

Apple has switched RAM yet again, as the Xeon 5150 requires fully-buffered DIMMs. I'll discuss those further in another section; here, I want to focus on adding and subtracting RAM.

The RAM riser

Instead of having to reach deep into the bowels of your case to slip the RAM into the slots, the Mac Pro uses a handy riser system. All you have to do is reach in, slide out the risers, insert your new RAM, and slide the risers back in. It works very smoothly.

My, what big heatsinks you have!

There are eight slots in total, four on each card. The slots are spaced wider than usual, which is necessary given the gargantuan heat sinks Apple is using on its chips. Apple says that it is using the heat sinks to "ensure that the fans run at the proper speed to maintain the optimal temperature and ensure acoustic performance." FB-DIMMs with conventionally sized heatsinks will work in the Mac Pro, although Apple recommends Apple-approved heatsinks "for optimum performance and acoustics."